McDonnell F3H Demon. The McDonnell F3H Demon naval fighter is chiefly remembered for the controversial delays and troubles suffered by its jet engine powerplants. The original J40 was a failure and brought the end of the original F3H-1 series but the J71 engine in the revised F3H-2, although not perfect, did help in the development of a decent service aircraft. Begun as an interceptor, Demon was a large and heavy single-seat fighter, it could reach supersonic speed in a dive with ease and one of the later versions became the Navy's first all-weather missile-firing fighter. In the air the Demon handled beautifully. The aircraft never took part in a major conflict but was on hand aboard U.S. Navy carriers between 1958 and 1965 in case any of the crisis situations of that period turned into a major conflict. In fact by 1965 the Demon had been present in the front line for longer than any previous U.S. Navy jet fighter. Despite such a shaky start and the "dark days" of its early versions, the Demon was ultimately a success.